Thermal tolerance in Spodoptera frugiperda: Influence of age, sex, and mating status

Abstract

Temperature plays a key role in shaping the physiology and behavior of ectotherms where responses can depend on age, sex and ontogeny. We investigated the effects of age, sex and mating status on thermal tolerance of Spodoptera frugiperda 3-, 6- and 9-days old adults heat shocked at adult, pupal and larval stages, at 40 °C for 2 h. Our results showed varied significant critical thermal maxima across mating status, age, sex and life stage in tested insects after heat shock. The virgin females CTmax increased with age while it fluctuated in males and 6 days old virgin females had higher CTmax than males. The 3 day old mated females had the highest heat tolerance while 6 days old virgin males the lowest heat tolerance. There was no significant difference in CTmax recorded between virgin males and females aged 3 and 9 days as well as 3, 6 and 9 day mated males and females. There was also no significant interaction between mating status and sex but there was a significant interaction effect between life stage and age. Mated males had higher CTmax than females across all heat shocked developmental stages. The results show a high level of fitness and survival in S. frugiperda females, which may be advantageous in invasion. This study also showed “carry over” effects in adults heat shocked at juvenile stage, with aged adults showing decline in CTmax. This study suggests that plasticity of thermal tolerance may be an important approach for S. frugiperda invasion.